The present invention relates generally to trucks used for mixing, hauling and pouring concrete and more specifically to a truck having a concrete mixing barrel which may be raised and lowered in elevation with respect to the truck body for the purpose of transporting the truck into low clearance areas such as storage garages and the like.
Concrete mixing trucks of the type having a concrete mixing barrel rotatably mounted on a rear frame portion of the truck have long been in use for transporting concrete, as between a batch plant and a job site. The concrete mixing barrel contains an interior screw device which urges the concrete towards the mouth of the barrel. The barrel is generally inclined in a forward downwardly sloping direction relative to the truck bed with an open end in a raised position at the rear of the truck. When it is desired to pour concrete, the barrel is revolved in a direction which causes the screw to move the concrete in the direction of the barrel opening. The concrete is discharged from the barrel opening into a hopper and chute arrangement which may be pivoted to deliver the concrete to various locations at the rear of the truck. During transportation of the concrete between batch plant and job site concrete is mixed by slowly revolving the barrel in a direction which moves the concrete towards the closed end of the barrel.
In order to effectively carry, mix, and pour concrete, concrete trucks have in the past been provided with barrels which are inclined at a substantial angle. If a barrel is positioned at too small an angle from the horizontal full loading of the barrel is impossible. However, when a barrel is positioned at a relatively large angle of inclination, the vertical clearance distance of the barrel is substantial, usually several feet more than the clearance distance of the truck cab.
It would be generally desireable to provide a concrete truck having a barrel which could be repositioned for storage or for transportation of the truck in low clearance working environments. It would be particularly desireable to provide a small concrete truck having a barrel which, in a raised position, could carry a full load of concrete and which could be lowered to carry smaller loads in restricted height work environments or to store the truck in a standard size garage having a clearance of about 7 feet. Such a truck should be designed in a manner which allows the barrel to be stabilized in both a raised and a lowered position.